Observations

Description

Valves elliptically lanceolate with slightly rostrate apices. The raphe valve has an off-set “bow tie” shaped to oval central area. The rapheless valve has a large, broad central area, becoming more narrow toward the apices. The raphe is straight with expanded, unilaterally deflected proximal ends. The distal raphe ends are deflected to opposite sides of the valve. The striae are radiate on the raphe valve and slightly radiate on rapheless valve. The striae are multiseriate.

Original Images

Cite This Page: Otu, M., and Spaulding, S. (2011). Planothidium holstii. In Diatoms of the United States. Retrieved August 02, 2015, from http://westerndiatoms.colorado.edu/taxa/species/planothidium_holstii

Valves are relatively large with slightly rostrate apices. The raphe valve has a distinct central area that is “bow tie” shaped. The rapheless valve has a large, broad central area, becoming more narrow toward the apices. Distal raphe ends are deflected to opposite sides of the valve.

Compare

The size range of P. holstii overlaps with P. apiculatum, but these taxa are distinct in several features. The apices are much more narrow in P. apiculatum. Furthermore, the striae of the raphe valve are more radiate. The rapheless valve of P. holstii lacks a hood, which is present in P. apiculatum.